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Patented Mar. l4, I899.

r. r. s'cuou.

DENTAL ENGINE.

(Application filed Oct. 5, 1897.)

3 Sheets-Shae! I.

(No Model.)

5 14mm oz 4 Fla aim TNE NORRIS nzrzns co, Pmnaumoq WASNINGTON. n, cy

Patented Mar. l4, I899.

F. F. SCHOLL.

DENTAL ENGINE.

(Application filed Oct. 6, 1897.)

3 Sheets$heet 2.

(No Model.)

@uventoz No. 621,154. Pa'tented Mar. l4, I899.

F. F. SCHOLL.

DENTAL ENGINE.

(Application filed Oct. 5, 1897.) (No Model.) 3 Sheets-Sheet 3.

Wane/may m: 'Nomns PETERS co, PNOTOJJTHQ, WASHINGTON. o. c

UNITED STATES Trice.

FREDERICK F. SCHOLL, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO JOHN HOOD & 00., OF SAME PLACE. I

DE-NTAL ENGINE.

SPECIFICATION forming part of Letters Patent No. 621,154, dated March 14, 1899.

Application filed October 1897. Serial No. 654,167. (No model.)

To all whom it may nc n: The invention consists in the novel con- Be it known that I, FREDERICK F. SCHOLL, struction, combination, and arrangement of a citizen of the United States, and a resident parts, such as will be hereinafter fully deof Boston, in the county of Suffolk and State scribed, pointed out in the appended claims, 5 of Massachusetts, have invented certain new and illustrated in the accompanyingdrawings. and useful Improvements in Dental Engines, In the accompanying drawings, in which of which the following is a full, clear, and similar letters of reference designate correexact description, such as will enable those sponding parts, Figure 1 is a side elevation skilled in the art to which it appertains to of a dental engine embodying the invention. IO make and use the same. Fig. 2 is an enlarged detail View showing a This invention relates to improvements in side elevation, partly in section and broken dental engines, and more particularly to the away in parts, of the pitman, treadle, and the dental engines shown and described in Patspring regulating device. Fig. 3 is asimilar ent No. 548,989, granted October 29, 1895, and view showing a front elevation of the same. I 5 in the application for patent filed by John Fig. lis a detail perspective view showing the Hood and Stephen H. Reynolds November 18, adj listing-bracket for the arm supporting the 1896, having Serial No. 612,536. flexible shafting. Fig. 5 is an enlarged de- The invention has for its objects the pro tail sectional view showing the hinge connecvision of a mechanism whereby the tension tion between the main and rocking standards, 20 of the spring for throwing the crank-shaftoff the crank-shaft, and the bearing for the latdead-center can be regulated and the proviter. Fig. 6 is an enlarged detail View showsion of a mechanism for preventing oil from ing a side elevation of the arm for supporting escapingfrom thebearing-sleeve intermediate the flexible shafting in connection with the of the pulley and the rod connected with the upper standard and the adjusting-bracket. 2 5 inner helix of the flexible shaft'ing. In this View the arm is shown in a depressed In dental engines where the pitman and position by dotted lines. Fig. 7 is a similar treadle are connected by a spring for throwview of the same, showing a rear elevation ing the crank-arm off dead-center, after the with the arm depressed. Fig. 8 is a sectional springhasbeen in useforsometimeitbecomes View of the same. Fig. 9 is a similar view 3o stretched, and consequently does not serve showing the telescopic covering for the sleeve its purpose so well. In the present instance extended. it is proposed to obviate this objectionable Referring to the drawings, A designates the feature by providing an adjusting mechanbase, which may be of any construction in the ism, so that the tension of the spring can be premises. The lower or supporting standard 8 5 3 5 regulated. Furthermore, in dental engines B is secured to the base in any suitable manwhere the sleeve in which is mounted the rod ner, and it has hinged to its upper end the connected with the inner helix of the flexible upper or rocking standard B. The hingeshafting and on which is mounted the drivjoint between the two standards is formed by ing-pulley and wheresaid sleeve has a movebifurcating the upper end of the supportingo 40 ment endwise in the casing in which it is standard and shaping the lower end of the journaled has more or less of its surface covrocking standard to fit the bifurcations. The ered with oil exposed. As the said sleeve is interlocking ends of the standards are prodriven at a high rate of speed, the oil is often vided with a transverse bearing in which is thrown off and soils surrounding objects. In mounted'the sleeve 0. The latter forms the 5 5 the present instance this is obviated by propintle for the hinge-joint. The two standards viding a sliding cover or shield that prevents are held in alinement by any of the wellany part of the sleeve from becoming exknown spring mechanisms used for the purposed and at the same time allows the sleeve pose. The mechanism shown in the said apto move back and forth to accommodate the plication is an instance. I00 50 pulley to the adj ustments of the operating- The sleeve 0 is extended at one end 0 and arm. projects into the hub of the fiy-Wheel E. In

the sleeve is journaled the driving-shaft F, which has an end extended beyond the sleeve and secured in the hub e of the fly-wheel by the screws 6'. In each end of the sleeve an annular recess 0 is formed in the inner periphery of the same. These recesses constitute bearing-surfaces. On the ends of the shaft F are mounted the bearing-cones fand f. The bearing-cone f is seated on the shaft within the hub of the fly-wheel and is held thereby in its proper relative position. The bearing-cone f is adjustably mounted on the shaft by being screwed thereon. Interposed between the bearings formed in the ends of the sleeve C and the bearing-cones are the bearin g-balls f By means of the adjustable bearing-cone f the wear between the several parts can be taken up. By this construction the shaft F bears on no part of the sleeve 0, as it is entirely supported by the bearingballs.

The crank-arm F is made integral with the shaft F. By making the two integral all danger of the two parts workingloose is obviated. In assembling the parts the cone f has to be placed on the shaft before the latter is mounted in its bearings. As the cone f cannot be placed on the shaft from the crank end, it is put on the opposite end and is moved on the shaft toward the crank end until it engages with the screw-threads, when it is turned until it comes against the crank-arm. The diameter of the smooth portion of the shaft is less than the screw-threaded portion. This allows the bearing-cone to be moved along the shaft until it engages with the threaded portion. After the bearing-conef has been placed on the shaft the latteris passed through the sleeve 0 and the bearing-cone f and secured to the fly-wheel E by the screws e. The bearing-balls having been previously put in place the several parts are snugly brought together by the adjustable bearing-cone f. The latter is secured against accidental displacement by the screw pin f passing through the crank-arm and engaging with a hole in the said bearing-cone. A hole f in the periphery of the bearing-cone allows the use of a tool for turning the said bearing-cone. I11 this way a hinge-joint between the standards and an antifriction-bearin g for the crankshaft is secured which allows a free movement of the rocking shaft, an easy running of the crank-shaft, and secures the crankarm against slipping on the crank-shaft.

The shaft F is driven by the pedal H, pivoted on the base and connected With the crank-arm F by the pitman II. The lower end of the pitman is hinged to the free end of the treadle by the pintle h. On this pintle an angular lever H is also pivoted. The latter is pivoted at its angle and is recessed to receive the lower end of the pitman. The angular lever has two arms h and 71. The arm h is connected with the under side of the pedal by the spring H Intermediate of the ends of the pitman a lug 71/ projects and is connected with the arm h by an adjusting mechanism,whereby the tension of the spring H can be regulated. This tension mechanism consists of the screw-threaded rod hinged at an end to the lug 7L3, the rod 7L5, oppositely threaded to the rod 70, hinged at an end to the arm 7t, and the double nut h, suitably threaded to receive the ends of the oppositely-threaded rods. By turning this nut one Way or the other the inner ends of the rods are either brought together or separated. This bringing together or separating of the rods moves the angular lever H and thereby regulates the tension of the spring H A lock nut IL7 is provided for securing the double nut against accidental displacement. By providing the spring with-this tension device as it becomes stretched by use the elongation can be taken up and the force with which the spring acts to throw the crank-arm ofi dead-center can be regulated.

To the upper end of the rocking standard B is attached the telescopic extension B In the upper end of the latter isswiveled the rod L, the upper end of which is bifurcated and formed into the curved arms Z. Between the said arms are pivoted the ends of the arms Z of the plate L. In the extension projecting from the upper face of the plate, is secured the casing L which carries the flexible shafting L and in which is mounted the mechanism for conveying motion to the inner helix of said shafting. The end Z of the casing projects to the rear of the extension Z In the casing is journaled the sleeve 1, having a movement back and forth therein as well as a rotary movement. The movement of the sleeve toward the end Z of the casing is limited by the collar l engaging with the shoulder Z. The sleeve projects from the end Z of the casing and has secured thereon the pulley L A screw-pin Z passes through the hub of the pulley and engages with an opening in the side of the sleeve. By striking against the end of the casing the pulley limits the forward movement of the sleeve. In the sleeve is the rear end of the rod L, that drives the inner helix of the flexible shafting. It is splined therein by the end of the screw-pin Z projecting into the sleeve Z and engaging with a groove in the said rod. The movement of the sleeve endwise in the casin g allows the pulley to automatically regulate itself to accommodate the belt leading from the fly-wheel as the casing is moved up or down or as the rod L moves in or out. As there is considerable friction between the sleeve Z and the casing, considerable oil is introduced between the two for lubricating purposes. This oil spreads over the sleeve, and as the latter moves back and forth in the casing more or less of its oiled surface is exposed at the end on which the pulley is mounted. As the sleeve is rotated at a high rate of speed, the oil has a tendency to escape from the exposed surface. This is prevented by the annular flange or shield Z projecting from the pulley and extending over the casing to form a telescopic covering for the exposed surface of the'sleeve projecting from the casing. The length of this flange is such as to always extend over the casing no matter to what extent the sleeve may project from the casing. The annular flange or shield covers that part of the sleeve that would otherwise be exposed and prevents the escape of the oil.

It is to be observed that the hinge connection between the casing L and the upper standard is such that when the sleeve is depressed it supports the flexible shafting almost vertically.

A mechanism is provided for adjustably supporting the casing L From the under side of the casing a lug N projects and has hinged thereto an end. of the bar N. The free end of the latter passes through a slot a, formed in the upper end of rod L, immediately below the place Where the arms Z come together. The under edge of the bar is notched at M, so that it will engage with the catch n projecting into the slot 72. The slot is of such formation as to give free play to the bar as the casing is either raised to a horizontal position or depressed to an almost vertical position. The upward movement of the casing is limited by the ball N on the free end of the bar coming into contact with the standard. The under face of the plate L is grooved at n to receive the arm when the casing is depressed. The ball N has considerable weight and serves to normally hold the free end of rod N depressed, and thereby obviates the use of a spring for the same purpose.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is-

1. In a dental engine, the combination of the treadle, the pitman hinged to the said treadle, the pintle connecting said treadle and said pitman, the angular lever pivoted on the said pintle, a spring connecting one arm of the said lever with the treadle, and a tension-regulating device connecting the other arm of said lever with said pitman.

2. In a dental engine, the combination of a treadle, a pitman, a pintle connecting said treadle and said pitman, an angular lever pivoted on said pintle, a spring connecting one arm of said lever with said treadle, and means for connecting the other arm of said lever-with said pitman.

3. In a dental engine, the combination of a casing, a rotatable sleeve journaled in said 4. In a dental engine, the combination of a casing, a rotatable sleeve journaled in said casing and projecting at an end from said casing, means for moving said sleeve endwise in said casing, a pulley mounted on the end of said sleeve projecting from the casing, and a shield extending from said pulley over the projecting end of said sleeve and having a telescopic connection with said casing.

5. In a dental engine, the combination of a casing, a sleeve journaled in said casing and having an endwise movement therein and projecting at an end from said casing, a rod splined in said sleeve and having an endwise movement therein, a pulley mounted on the end of said sleeve projecting from the casing, a shield extending from said pulley over the projecting end of said sleeve and having a telescopic connection with said casing.

6. In a dental engine, the combination of a casing, a rotatable sleeve journaled in said casing and having a limited endwise move ment therein, a pulley carried by said sleeve, a drivingrod mounted in said sleeve and having an endwise movement therein, and means for connecting said sleeve with said rod so that rotatable motion will be conveyed from one to the other and so as to allow said rod to move longitudinally in said sleeve.

7. In-a dental engine, the combination of a casing, a rotatable sleeve journaled in said casing and having a limited endwise movement therein, a driving-rod having an'endwise movement in said sleeve and having a longitudinal groove in its periphery, and a screw-pin passing through said sleeve and registering with said groove.

In testimony whereof I hereunto affix my signature in the presence of two witnesses.

FREDERICK F. SOHOLL.

Witnesses:

H. H. NEWooMB, M. O. DUFFY. 

